The alteration by which the number of morphemes in an utterance fails in some cases to coincide with the number of morphs consists of recognizing two special kinds of morph: "empty morphs", which have no meaning and belong to no morpheme; and "portmanteau morphs", which belong simultaneously to two (or, theoretically, more) morphemes, and have simultaneously the meanings of both.
- Hockett (2004a), Pag. 82